Preparation of modified MOFs catalyst and method for preparing propylene glycol by catalyzing saccharides through modified MOFs catalyst

Abstract

The invention provides preparation of a modified MOFs catalyst and a method for preparing propylene glycol by catalyzing saccharides through the modified MOFs catalyst, and belongs to the technical field of chemical reagent preparation. The modified MOFs catalyst disclosed by the invention is obtained by taking a metal-organic framework as a carrier and carrying out tungsten oxide and transition metal post-modification on the metal-organic framework, the catalyst can retain a crystal structure of MOFs, and the recovered catalyst does not have an obvious structure collapse phenomenon. The catalyst provided by the invention can realize complete conversion of saccharides under a liquid phase condition at a relatively mild temperature and ultralow hydrogen pressure, high-selectivity synthesis of dihydric alcohol with industrial value is realized, propylene glycol is used as a main product, and the catalyst has the characteristics of repeated recycling, high temperature resistance, decomposition resistance, environmental friendliness and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical reagent preparation, and in particular relates to a method for preparing a modified MOFs catalyst and catalyzing sugars to prepare propylene glycol. Background Art

[0002] Considering the increasing depletion of fossil resources, the development and utilization of sustainable energy to partially replace fossil resources to meet the huge needs of today's human society has attracted great attention. Among these renewable resources, biomass has the advantages of wide sources, less pollution and potential economy, and is considered to be one of the most important sustainable resources. Many catalytic systems have been designed to realize the value of biomass. Diols (ethylene glycol, propylene glycol and butanediol) are important and valuable chemicals. Among them, propylene glycol is an important raw material for the synthesis of useful chemicals such as surfactants and plasticizers, and is also an end product used in the pharmaceutical, food and refrigeration industries. Typical production methods of propylene glycol include petroleum product conversion and direct biomass hydrogenolysis. Relatively speaking, biomass hydrogenolysis is considered to be a green and environmentally friendly method because there are enough biological raw materials in biomass, such as various sugars such as glucose, fructose, sucrose, xylose and inulin.

[0003] At present, most of the research on the catalytic conversion of sugars into diols in the field of chemical technology requires harsh conditions such as high temperature, high pressure and long reaction time, which leads to the increase of the cost of raw materials, energy consumption and reaction equipment. In addition, it is impossible to enter the production and trading market of bulk chemicals, which limits the application areas of sugar conversion into diols. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for preparing a modified MOFs catalyst and catalyzing sugars to prepare propylene glycol.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] A method for preparing a modified MOFs catalyst, using a metal-organic framework (MOFs) as a carrier, and treating the MOFs with tungsten oxide (WO x ) and transition metal (M) to obtain the modified MOFs catalyst (M-WO x -MOFs catalysts).

[0008] Furthermore, the loading amount of the transition metal on the metal-organic framework is 1wt%-5wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3wt%-10wt%.

[0009] Furthermore, the transition metal includes one or more of Ni, Cu, Ru, Pt and Pd.

[0010] Furthermore, the MOFs is one of MOF-74, UIO-66, MIL-101, MIL-125, HKUST-1 and ZIF-8.

[0011] Further, the post-modification comprises the following steps:

[0012] The metal-organic framework, tungsten hexachloride (WCl6) and a transition metal precursor are mixed and dissolved to obtain a mixed solution, and the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and vacuum dried at 60° C. overnight to obtain the modified MOFs catalyst;

[0013] Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst.

[0014] Furthermore, the mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 hours.

[0015] Furthermore, the reduction reaction is carried out at a temperature of 200° C. and for a period of 4 hours.

[0016] Furthermore, the transition metal precursor includes one or more of nickel chloride hexahydrate (NiCl2·6H2O), cupric chloride dihydrate (CuCl2·2H2O), ruthenium trichloride hydrate (RuCl3·xH2O), sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O) and palladium chloride (PdCl2).

[0017] The second technical solution of the present invention:

[0018] A modified MOFs catalyst prepared by the preparation method.

[0019] The catalyst can retain the crystal structure of MOFs, and the recycled catalyst will not have obvious structural collapse.

[0020] The third technical solution of the present invention:

[0021] A method for preparing propylene glycol by catalyzing sugars, using the modified MOFs catalyst as a catalyst, mixing with sugars and a solvent, and then sealing the reaction to achieve the conversion of sugars into diols.

[0022] Furthermore, the mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

[0023] Furthermore, the sealing reaction is carried out at a temperature of 120-180° C. and for a time of 1-6 hours.

[0024] Furthermore, the solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

[0025] Furthermore, the diols include ethylene glycol, propylene glycol and butylene glycol, wherein propylene glycol is the main product.

[0026] Furthermore, the method for preparing propylene glycol from sugars using a modified MOFs catalyst specifically comprises the following steps:

[0027] 10-200 mg of catalyst, 100 mg of sugar and 10 mL of solvent are added into the reactor, and then the reactor is sealed and flushed with H2 for several times to remove the air in the reactor. Then the reactor filled with 0.2 MPa H2 is heated to 120-180 ° C and stirred at 500 revolutions per minute for 1-6 hours. After the reaction is completed, the solid catalyst is collected by centrifugation, and the supernatant is passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography to achieve the conversion of sugars into diols.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) The present invention uses sugars converted from biomass as raw materials and synthesizes M-WO by a simple hydrothermal method. x -MOFs catalyst can be used to catalyze the reaction in one kettle to produce diols with high selectivity, with propylene glycol as the main product. x -MOFs catalyst can catalyze the complete conversion of sugars and obtain a high yield of propylene glycol. After repeated recycling, the catalytic efficiency of the catalyst has not been significantly reduced, and the recovered catalyst retains the intact MOFs structure. It has the characteristics of being recyclable, high temperature resistant, not afraid of decomposition, and environmentally friendly. The total diol yield is 70%, of which the yield of propylene glycol can reach 54%.

[0030] (2) The present invention directly synthesizes the target product in one kettle at a relatively low temperature without any intermediate steps. The target product can be obtained by filtering the reaction solution, so the economic benefits can be increased. The product selectivity of the whole process is relatively high, the operation is simple, the process is short, the cost is low, the safety is high, and the process is green. It has good prospects for industrial application and has certain strategic significance for the development of the chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 M-WO x - Reaction flow chart of the conversion of glucose into diols catalyzed by MOFs catalyst;

[0033] Figure 2 The Pt-WO recovered in Application Example 1 x -MOF-74(Co) and pristine Pt-WO x -XRD pattern of MOF-74(Co). DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0038] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] The present invention provides a method for preparing a modified MOFs catalyst, using a metal-organic framework (MOFs) as a carrier, and performing tungsten oxide (WO x ) and transition metal (M) to obtain the modified MOFs catalyst (M-WO x -MOFs catalysts).

[0040] In a preferred embodiment of the present invention, the loading amount of the transition metal on the metal-organic framework is 1 wt%-5 wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3 wt%-10 wt%.

[0041] In a preferred embodiment of the present invention, the transition metal includes one or more of Ni, Cu, Ru, Pt and Pd.

[0042] In a preferred embodiment of the present invention, the MOFs is one of MOF-74, UIO-66, MIL-101, MIL-125, HKUST-1 and ZIF-8, which are commercially available.

[0043] In a preferred embodiment of the present invention, the post-modification comprises the following steps:

[0044] The metal-organic framework, tungsten hexachloride (WCl6) and a transition metal precursor are mixed and dissolved to obtain a mixed solution, and the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and vacuum dried at 60° C. overnight to obtain the modified MOFs catalyst;

[0045] Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst.

[0046] In a preferred embodiment of the present invention, the mixed solution is transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 hours.

[0047] In a preferred embodiment of the present invention, the reduction reaction temperature is 200° C. and the time is 4 hours.

[0048] In a preferred embodiment of the present invention, the transition metal precursor includes one or more of nickel chloride hexahydrate (NiCl2·6H2O), cupric chloride dihydrate (CuCl2·2H2O), ruthenium trichloride hydrate (RuCl3·xH2O), sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O) and palladium chloride (PdCl2).

[0049] The embodiment of the present invention also provides a modified MOFs catalyst prepared by the preparation method.

[0050] The embodiment of the present invention also proposes a method for preparing propylene glycol by catalyzing sugars, using the modified MOFs catalyst as a catalyst, mixing with sugars and a solvent, and then sealing the reaction to achieve the conversion of sugars into diols.

[0051] In a preferred embodiment of the present invention, the mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

[0052] In a preferred embodiment of the present invention, the sealing reaction is carried out at a temperature of 120-180° C. and for a time of 1-6 hours.

[0053] In a preferred embodiment of the present invention, the solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

[0054] In a preferred embodiment of the present invention, the diol comprises ethylene glycol, propylene glycol and butylene glycol, wherein propylene glycol is the main product.

[0055] All raw materials used in the examples of the present invention are commercially available.

[0056] The technical solution of the present invention is further illustrated by the following embodiments.

[0057] Example 1

[0058] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0059] 0.2 g of metal-organic framework (MOF-74(Co)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Co).

[0060] Pt-WO x -In the MOF-74(Co) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.4wt%, and the loading amount of tungsten oxide on the metal-organic framework is 6.2wt%.

[0061] Example 2

[0062] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0063] 0.2 g of metal-organic framework (MOF-74(Ni)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Ni)).

[0064] Pt-WO x -In the MOF-74(Ni) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.3%, and the loading amount of tungsten oxide on the metal-organic framework is 4.9wt%.

[0065] Example 3

[0066] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0067] 0.2 g of metal-organic framework (MOF-74(Mg)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Mg)).

[0068] Pt-WO x -In the MOF-74(Mg) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.2%, and the loading amount of tungsten oxide on the metal-organic framework is 5.6%.

[0069] Example 4

[0070] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0071] 0.2 g of metal-organic framework (Uio-66(Zr)), 0.01 g of tungsten hexachloride (WCl6) and 0.005 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -Uio-66(Zr)).

[0072] Pt-WO x -Uio-66(Zr) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 2.3%, and the loading amount of tungsten oxide on the metal-organic framework is 3.4%.

[0073] Example 5

[0074] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0075] 0.2 g of metal-organic framework (Uio-66(Ce)), 0.01 g of tungsten hexachloride (WCl6) and 0.005 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -Uio-66(Ce)).

[0076] Pt-WO x -Uio-66(Ce) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 2.1%, and the loading amount of tungsten oxide on the metal-organic framework is 3.6%.

[0077] Example 6

[0078] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0079] 0.2 g of metal-organic framework (MIL-101(Fe)), 0.07 g of tungsten hexachloride (WCl6) and 0.02 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-101(Fe)).

[0080] Pt-WO x - In the MIL-101(Fe) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 4.8%, and the loading amount of tungsten oxide on the metal-organic framework is 9.8wt%.

[0081] Example 7

[0082] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0083] 0.2 g of metal-organic framework (MIL-101(Cr)), 0.07 g of tungsten hexachloride (WCl6) and 0.02 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-101(Cr)).

[0084] Pt-WO x - In the MIL-101(Cr) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 5%, and the loading amount of tungsten oxide on the metal-organic framework is 10.0wt%.

[0085] Example 8

[0086] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0087] 0.2 g of metal-organic framework (MIL-125(Ti)), 0.05 g of tungsten hexachloride (WCl6) and 0.007 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-125(Ti)).

[0088] Pt-WO x - In the MIL-125(Ti) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 3.0wt%, and the loading amount of tungsten oxide on the metal-organic framework is 7.2wt%.

[0089] Example 9

[0090] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0091] 0.2 g of metal-organic framework (HKUST-1(Cu)), 0.05 g of tungsten hexachloride (WCl6) and 0.015 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160 °C for 24 h, then washed and dried in vacuum at 60 °C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -HKUST-1(Cu)).

[0092] Pt-WO x -HKUST-1(Cu) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 3.2%, and the loading amount of tungsten oxide on the metal-organic framework is 8.8wt%.

[0093] Example 10

[0094] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0095] 0.2 g of metal-organic framework (ZIF-8(Zn)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution, which was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -ZIF-8(Zn)).

[0096] Pt-WO x - In the ZIF-8(Zn) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.3wt%, and the loading amount of tungsten oxide on the metal-organic framework is 6.6wt%.

[0097] Application Example 1

[0098] 50 mg of M-WO prepared in Examples 1 to 10 was added into the reactor. x -MOFs catalyst, 100 mg glucose and 10 mL water, then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor, then the reactor filled with 0.2 MPa H2 was heated to 160 ° C and stirred at 500 revolutions per minute for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was filtered through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. x The reaction performance results of MOFs catalysts to generate diols are shown in Table 1. Taking glucose as an example, the reaction flow chart of catalytic conversion of sugars into diols is shown in Figure 1 .

[0099] Table 1 Different M-WO x -MOFs catalyst reaction performance results for diol production

[0100]

[0101]

[0102] Application Example 2

[0103] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x-MOF-74(Co) catalyst, 100 mg of sugar (glucose, fructose, sucrose, xylose or inulin) and 10 mL of water were added, and then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor. Then the reactor filled with 0.2 MPa H2 was heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. The reaction performance results of generating diols when different sugars were used as substrates are shown in Table 2.

[0104] Table 2 Reaction performance results of diols produced when different sugars are used as substrates

[0105] Substrate Conversion rate / % Diol yield / % Propylene glycol yield / % glucose 100 70 54 fructose 100 75 56 sucrose 100 50 40 Xylose 100 45 35 Inulin 100 40 38

[0106] Application Example 3

[0107] Add 10-200 mg of Pt-WO prepared in Example 1 into the reactor. x -MOF-74(Co) catalyst, 100 mg of sugar (glucose) and 10 mL of water were added, and the reactor was then sealed and flushed with H2 for several times to remove the air in the reactor. The reactor filled with 0.2 MPa H2 was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. The reaction performance results of glucose to diols at different catalyst dosages are shown in Table 2.

[0108] Table 3 Reaction performance results of glucose to diols at different catalyst dosages

[0109] Catalyst / mg Conversion rate / % Diol yield / % Propylene glycol yield / % 10 100 60 45 30 100 69 52 50 100 70 54 100 100 72 54 200 100 76 52

[0110] Application Example 4

[0111] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg glucose and 10 mL water, then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor, then the reactor filled with 0.2 MPa H2 was heated to 120-180°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. The reaction performance results of glucose to produce diols at different reaction temperatures are shown in Table 4.

[0112] Table 4 Reaction performance results of glucose to diols at different reaction temperatures

[0113] Reaction temperature / ℃ Conversion rate / % Diol yield / % Propylene glycol yield / % 120 20 20 10 140 64 34 22 160 100 70 54 180 100 74 52

[0114] Application Example 5

[0115] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74 (Co) catalyst, 100 mg of sugar (glucose) and 10 mL of water, then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor, then the reactor filled with 0.2 MPa H2 was heated to 160°C and stirred at 500 rpm for 1-6 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, the supernatant was passed through a filter with a pore size of 0.22 μm, and then analyzed by high performance liquid chromatography. The reaction performance results of glucose to produce diols at different reaction times are shown in Table 5.

[0116] Table 5 Reaction performance results of glucose to diols at different reaction times

[0117] Reaction time / h Conversion rate / % Diol yield / % Propylene glycol yield / % 1 65 30 19 2 76 38 26 4 100 70 54 6 100 60 50

[0118] Application Example 6

[0119] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg of sugar (glucose) and 10 mL of solvent (water, ethanol, cyclohexane, isopropanol or and γ-valerolactone), then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor, then the reactor filled with 0.2 MPa H2 was heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, the supernatant was passed through a filter with a pore size of 0.22 μm, and then analyzed by high performance liquid chromatography. The reaction performance results of glucose to form diols in different reaction solvents are shown in Table 6.

[0120] Table 6 Reaction performance results of glucose to diols in different reaction solvents

[0121] Reaction solvent Conversion rate / % Diol yield / % Propylene glycol yield / % water 100 70 54 Ethanol 100 66 48 Cyclohexane 100 69 50 Isopropyl alcohol 100 50 30 γ-Valerolactone 100 65 40

[0122] Combining the contents in Tables 1 to 6, it can be seen that M-WO x -MOFs can effectively convert glucose into diols, and the products are mostly concentrated in ethylene glycol; Pt-WO x -MOF-74(Co) is universal in the preparation of binary processes from various sugars, and diols will also be generated when the solvent is changed.

[0123] The Pt-WO collected by centrifugation in Application Examples 1 to 6 was x-MOF-74(Co) catalyst was subjected to catalytic cycle experiment according to the method in Example 2, with glucose as substrate. The reaction performance results of the recovered catalyst in catalyzing glucose to produce diols are shown in Table 7.

[0124] Table 7 Pt-WO x -The reaction performance results of glucose to diols after multiple cycles of MOF-74(Co) catalyst

[0125] Cycle times Conversion rate / % Diol yield / % Propylene glycol yield / % 1 100 70 54 2 100 70 54 3 100 69 53 4 100 70 55 5 100 69 53

[0126] Pt-WO after recycling in Application Example 1 x -MOF-74(Co)(Recycled-Pt-WO x -MOF-74(Co)) has the same XRD peak pattern as the original Pt-WO x -MOF-74(Co)(Fresh-Pt-WO x -MOF-74(Co)) Figure 2 ).

[0127] From Table 7 and Figure 2 It can be seen that after multiple cycles of use, the catalytic efficiency of the catalyst of the present invention is not significantly reduced, and the recovered catalyst retains the intact MOFs structure, and has the characteristics of being recyclable, resistant to high temperatures, not afraid of decomposition, and environmentally friendly.

[0128] Example 11-Example 20

[0129] The same as Example 1-10, except that the preparation is carried out by an impregnation method, and the specific preparation method is as follows:

[0130] Tungsten hexachloride and transition metal precursor, ruthenium trichloride hydrate and sodium hexachloroplatinate hexahydrate were mixed and dissolved in 10 mL of anhydrous ethanol to obtain a mixed solution. The mixed solution was impregnated on the metal-organic framework and stirred in a water bath (70°C) until the ethanol was completely evaporated. The solid powder was then reduced in a tubular furnace under a hydrogen atmosphere for 4 hours at a reduction temperature of 200°C and a heating rate of 5°C / min to prepare a catalyst.

[0131] The types and amounts of each raw material are exactly the same as those in Examples 1-10.

[0132] The catalyst prepared in Example 11 is denoted as Pt-WO x -MOF-74(Co)-1.

[0133] The catalyst prepared in Example 12 is denoted as Pt-WO x -MOF-74(Ni)-1.

[0134] The catalyst prepared in Example 13 is denoted as Pt-WO x -MOF-74(Mg)-1.

[0135] The catalyst prepared in Example 14 is denoted as Pt-WO x -Uio-66(Zr)-1.

[0136] The catalyst prepared in Example 15 is denoted as Pt-WO x -Uio-66(Ce)-1.

[0137] The catalyst prepared in Example 16 is denoted as Pt-WO x -MIL-101(Fe)-1.

[0138] The catalyst prepared in Example 17 is denoted as Pt-WO x -MIL-101(Cr)-1.

[0139] The catalyst prepared in Example 18 is denoted as Pt-WO x -MIL-125(Ti)-1.

[0140] The catalyst prepared in Example 19 is denoted as Pt-WO x -HKUST-1(Cu)-1.

[0141] The catalyst prepared in Example 20 is denoted as Pt-WO x -ZIF-8(Zn)-1.

[0142] Application Example 7

[0143] 50 mg of the catalyst prepared in Examples 11 to 20, 100 mg of glucose and 10 mL of water were added to the reactor respectively, and then the reactor was sealed and flushed with H2 for several times to remove the air in the reactor. The reactor filled with 0.2 MPaH2 was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. The reaction performance results of different catalysts to produce diols are shown in Table 8.

[0144] Table 8 Reaction performance results of different catalysts to generate diols

[0145]

[0146]

[0147] It can be seen from the data in Table 1 and Table 8 that the present invention uses the M-WOx-MOFs catalyst synthesized by a simple hydrothermal method for catalysis, can react in one kettle, and prepare diols with high selectivity. Under mild reaction temperature and ultra-low hydrogen pressure conditions, the M-WOx-MOFs catalyst can catalyze the complete conversion of sugars and obtain propylene glycol with a high yield. Compared with the technical solution of the in-situ hydrothermal method in the embodiment of the present invention, the catalyst prepared by the impregnation method has better performance because the hydrothermal method avoids the agglomeration of metal particles.

[0148] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a modified MOFs catalyst, characterized in that: The metal-organic framework is used as a carrier, and tungsten oxide and transition metal are post-modified to obtain the modified MOFs catalyst.

2. The method for preparing the modified MOFs catalyst according to claim 1, characterized in that: The loading amount of the transition metal on the metal-organic framework is 1 wt%-5 wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3 wt%-10 wt%.

3. The method for preparing the modified MOFs catalyst according to claim 1, characterized in that: The transition metal includes one or more of Ni, Cu, Ru, Pt and Pd.

4. The method for preparing the modified MOFs catalyst according to claim 1, characterized in that: The post-modification comprises the following steps: The metal-organic framework, tungsten hexachloride and a transition metal precursor are mixed and dissolved to obtain a mixed solution, the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and vacuum dried to obtain the modified MOFs catalyst; Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst.

5. The method for preparing the modified MOFs catalyst according to claim 4, characterized in that: The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 h; The temperature of the reduction reaction is 200° C. and the time is 4 hours.

6. A modified MOFs catalyst prepared by the preparation method according to any one of claims 1 to 5.

7. A method for preparing propylene glycol by catalyzing sugars, characterized in that: The modified MOFs catalyst according to claim 6 is used as a catalyst, mixed with sugars and a solvent, and then the reaction is sealed to achieve the conversion of sugars into diols.

8. The method for preparing propylene glycol by catalyzing sugars according to claim 7, characterized in that: The mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

9. The method for preparing propylene glycol by catalyzing sugars according to claim 7, characterized in that: The sealing reaction is carried out at a temperature of 120-180° C. and for a time of 1-6 hours.

10. The method for preparing propylene glycol by catalyzing sugars according to claim 7, characterized in that: The solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

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